Eleven windows were smashed at the venue at the heart of community life in what has been called a "disheartening" strike.

The damage was done on the eve of a major race meeting for the town as volunteers were doing their best to make the course shine for the event, the first since the death of race club president and industry stalwart Douglas Egan last week.

Police are investigating the break-in and damage that was reported early on Saturday morning.

Inspector Gemini Bakos said the venue had been hired for a private party on Friday night, where there were 80 patrons in attendance.

It ended at 1.30am on Saturday and as partygoers left a fight broke out between some men and then more people became involved and it turned into a brawl.

The inspector said police were able to control the situation quickly.

At 6.45am some people involved with the party had returned to clean up and reported finding broken windows and a fire extinguisher and water cooler on the grass outside the building, she said.

An unknown person of interest or more than one person had forced entry at the locked security door to the side of the main racecourse building, she said.

It appeared they had used the fire extinguisher inside and thrown two large bricks through several windows, she said.

The inspector appealed to anyone with information about the break-in and damage to contact Narromine police or Crime Stoppers.

Narromine Shire Council, the trustee of the Crown land that hosts the race club, the show society, horse trainers and the pony club, learnt of the damage on Saturday.

Council general manager Greg Lamont this week condemned the "irresponsible" deed as he told of the people of the town rallying to fix the mess.

He said race club volunteers had discovered the 11 smashed dining room windows on Saturday morning when they arrived to prepare for a luncheon at Sunday's Narromine Gold Cup.

They notified the council, and Mr Lamont said it moved immediately to rectify the damage as quickly as possible, but it was "disheartening".

The general manager estimated the cost to the council of repairing the damage would be "up to or even a little more than $5000".

He said the cost to the council would be covered by insurance, but if the time of volunteers was taken into account, the damage would be "well in excess of $5000".

And the "frustrated" general manager viewed it as more than a monetary blow.

"All the users of the showground do a wonderful job, they take pride in their work," Mr Lamont said.

"They put their heart and soul into it to keep it at such a nice condition.

"It breaks their heart (to see this damage)."

Mr Lamont praised those who had the facility ready for the race meeting, a significant event on the shire's calendar.

"Our maintenance officer gave up his Saturday afternoon to fix this irresponsible activity by someone in the community," he said.

"He's a Narromine person committed to the community and its facilities.

"And our local hardware store, Treseders, did the same.

"That's the spirit of Narromine, we rally together."

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